Oral extended-release solid dosage forms for drug substances are highly desired. Hydrogel tablets made of a hydrogel polymer form a viscous layer at tablet surface during dissolution. The viscous layer retards the drug release from the tablet matrix. The manufacturing process usually is simple and straight-forward, no tedious functional coating process is needed. However, specific excipients (i.e. inactive ingredients) are required to achieve the desired in vivo performances. For instance, U.S. Pat. App. Pub. No. 20090011019 teaches specific excipient is needed for increasing the residence time of the composition disclosed in the gastro-intestinal tract. U.S. Pat. App. Pub. No. 20100285114 teaches the presence of a rate controlling polymer in a drug particle composition to achieve extended release.
Excipients available include but not limited to solubilizing agents, swelling agents, swell-controlling agents, gas generating materials, diluents, binders, disintegrants, lubricants, anti-sticking agents, and glidiants etc.
Excipients usually exist as a single chemical entity. Examples include but not limited to microcrystalline cellulose, hydroxypropyl methylcellulose, polyethylene oxide, polyvinyl pyrrolidone, dextrin, dextrose, fructose, lactitol, mannitol, sucrose, starch, lactose, xylitol, sorbitol, talc, microcrystalline cellulose, calcium carbonate, calcium phosphate dibasic or tribasic, calcium sulphate, zinc stearate, polyethylene glycol, glyceryl behenate, mineral oil, sodium stearyl fumarate, stearic acid, silicon dioxide; magnesium trisilicate, powdered cellulose, starch, talc and tribasic calcium phosphate, calcium silicate, magnesium silicate, colloidal silicon dioxide, hydrogenated vegetable oil and talc.
While excipients can also be a combination of two or more chemical entities. U.S. Pat. No. 6,391,352 teaches a starch/gum based ingredient for use in food products. U.S. Pat. No. 7,998,505 teaches a “microcrystalline cellulose containing material” consists of microcrystalline cellulose co-processed with carboxymethyl cellulose. U.S. Pat. No. 7,776,358 teaches a matrix material co-processed calcium phosphate and fatty acid wax. U.S. Pat. No. 5,747,067 teaches particulate pharmaceutical tablet excipient compositions comprising co-processed microcrystalline cellulose and particulate USP calcium carbonate. PCT/JP2007/071919 teaches an excipient and an enteric coating agent granulated while spraying a solution or suspension of a pharmaceutical component, thereby producing a granule A. The granule A is mixed with a mixture B which contains a hydrogel-forming substance, and the resulting mixture is shaped into a tablet. EP2090298 teaches a method comprises mixing (1) a granulated product A obtained by granulating an excipient and an enteric coating agent while spraying thereon with a solution or a suspension containing an orally administrable medicinal component, with (2) a composition B containing a hydrogel-forming substance; and then compressing the resulting mixture into a tablet. The chemical entities in these “combo excipients” are evenly distributed over the particle matrix. While the claimed matter in this application is a particle containing a core and an acid-soluble polymer, which may allow a bigger flexibility in the excipient selection for hydrogel tablet development.